Common House Spider

Parasteatoda tepidariorum

Size4–8 mm body length

Colony Size1–1

Active Season:Active year-round indoors. Web-building visible when cleaning is infrequent.

Small cobweb-building spider found in corners and undisturbed areas. Harmless and beneficial—preys on household insects.

Anatomy

Anatomical Details

Identification

ColourBrown to tan with mottled pattern, bulbous abdomen

Size4–8 mm body length

Distinguishing Features

Bulbous abdomen with mottled brown pattern, larger than cephalothorax
Builds messy, three-dimensional 'tangle webs' (not geometric orb webs)
Long, thin legs with faint dark rings, no obvious spines
Eight eyes in two rows
Completely harmless to humans—no medically significant bite

Similar Species

Brown Recluses do NOT exist in Canada. House Spiders are sometimes mistaken for them due to similar brown coloration, but they lack the characteristic violin marking on the cephalothorax and have a distinctly bulbous abdomen. There are no medically significant spiders established in most of Canada.
Larger spider (up to 18mm) with sheet-like webs featuring a funnel retreat in one corner. Also completely harmless. House Spider webs are chaotic 3D tangles, not flat sheets with funnel retreats.

Biology

Lifecycle

Females live 1+ year, males shorter. Egg sacs contain 150-400 eggs. Multiple sacs per female.

Diet

Effective pest controllers—preys on house flies, mosquitoes, ants, and even other spiders. A single house spider can consume hundreds of insects per year.

Nesting

Builds irregular, chaotic 3D 'tangle webs' in corners, window frames, and undisturbed storage areas. If a web doesn't yield food, they abandon it and build another elsewhere—leading to the accumulation of 'cobwebs' in neglected corners. Female remains in or near the web.